The present invention relates to a radio paging receiver that can receive and store a message signal specific to the receiver.
In general, such a message signal carries message information. Heretofore, among such type of radio paging receivers, those having a capability of protecting messages so that stored messages may not be erased, have been known. With regard to the methods for protecting memory contents, the following two methods are known:
(1) A method of employing a power supply for memory backup that is provided separately from a main power supply or source of the radio receiver (a backup method); and
(2) A method of mechanically protecting erroneous operation of a switch of the main power supply (a mechanical countermeasure method).
As will later be described with reference to five figures of the accompanying drawings, the above-mentioned methods in the prior art respectively have the following shortcomings. In the first place, the backup method is disadvantageous in the aspect of cost and small-sizing of the radio receiver. This is because a battery to be solely used for backup purpose is necessitated in addition to the main power supply. In addition, in practical use, although the radio paging receiver can protect data, a possessor of the receiver cannot know whether or not messages unconfirmed by the possessor are present within a memory in the radio paging receiver.
The mechanical countermeasure method is defective in that perfect protection of messages is impossible when the switch has been slid while it is depressed.